Euclid of Alexandria
Often referred to as the 'Father of Geometry,' his work 'Elements' is one of the most influential mathematical treatises in history.
Quotes by Euclid of Alexandria
A rectilinear figure is a figure contained by straight lines.
A rectilinear solid is a solid contained by plane surfaces.
An angle is the inclination to one another of two lines in a plane which meet one another and do not lie in a straight line.
When a straight line set up on a straight line makes the adjacent angles equal to one another, all the angles are right.
An obtuse angle is that which is greater than a right angle.
A figure is that which is contained by any one or more boundaries.
A diameter of a circle is any straight line drawn through the centre and terminated in both directions by the circumference.
A semicircle is the figure contained by a diameter of a circle and the circumference cut off by it.
To describe a circle with any centre and distance.
If a straight line falling on two straight lines make the interior angles on the same side less than two right angles, the two straight lines, if produced indefinitely, meet on that side on which are the angles less than the two right angles.
On a given finite straight line to construct an equilateral triangle.
To place a straight line equal to a given straight line with one end at a given point.
To cut off from the greater of two given unequal straight lines a straight line equal to the less.
If two triangles have two sides and the included angle equal, they will also have the base and the remaining angles equal.
In isosceles triangles the angles at the base are equal to one another, and, if the equal straight lines are produced further, the angles under the base are equal to one another.
If a straight line falling on two straight lines make the exterior angle equal to the interior and opposite angle on the same side, or if it make the interior angles on the same side together equal to two right angles, the straight lines will be parallel to one another.
Things which are equal to the same thing are equal to one another; this is the foundation of all reasoning in geometry.
Geometry is the knowledge of the eternal.
The laws of nature are written in the language of mathematics.
In the vastness of the cosmos, straight lines lead to truth.